Abstract: The invention relates to a stabilizer for L-012 or a salt thereof, a stabilization method for L-012 or a salt thereof, coexisting with the stabilizer and L-012 or a salt thereof, and the like. The stabilizer is represented by Formula [1]: wherein p pieces of M1 each independently represent a hydrogen atom or an alkali metal atom, q pieces of R1 each independently represent a hydroxy group or a sulfonic acid group, m represents 0 or 1, p represents an integer of 1 to 3, q represents an integer of 0 to 4, Y represents a nitrogen atom or a CH group (a methine group), and Z represents an aryl group having a specific structure or a pyrazolyl group having a specific structure.

Abstract: The invention relates to a stabilizer for L-012 or a salt thereof, a stabilization method for L-012 or a salt thereof, coexisting with the stabilizer and L-012 or a salt thereof, and the like. The stabilizer is represented by Formula [1]: wherein p pieces of M1 each independently represent a hydrogen atom or an alkali metal atom, q pieces of R1 each independently represent a hydroxy group or a sulfonic acid group, m represents 0 or 1, p represents an integer of 1 to 3, q represents an integer of 0 to 4, Y represents a nitrogen atom or a CH group (a methine group), and Z represents an aryl group having a specific structure or a pyrazolyl group having a specific structure.